The invention relates to an air filter system for a reciprocating piston internal combustion engine with an air filter disposed in a filter housing connected to a clean air line extending to the engine air intake system and means for damping the air intake noise.
DE 23 42 154 A1 discloses a noise damping air filter element for reducing the air intake noise, in particular for compressors and air induction machines in which a two-component housing forms an ellipse in a longitudinal section, and in which two housing halves are each filled with open-pore PUR foam beyond the focal point of the ellipse and connected in a seal-forming fashion.
The total noise of a motor vehicle is mainly made up of the noise sources of the intake system, engine, exhaust system, power transmission system, chassis, fans and tires. In addition to the attention being paid both to reducing the noise emissions from the various noise sources of a motor vehicle attention is increasingly given to the damping of the noise generated by the air filter system at the air intake side. The noises generated in the internal combustion engines result essentially from engine vibrations, internal pressure pulsations and the combustion process. The intake noises, such as, for example, internal pressure pulsations which travel out of the engine and to the air filter through the air intake manifold, hot film air mass flow rate meter (HFM) and air lines, are usually damped by resonators and by a corresponding air filter volume. However, this damping is not sufficient and the wall of the air filter nevertheless emits noise which travels into the passenger compartment. So-called large-area voluminous mats of damping material are frequently used in the air filters in order to reduce or eliminate this kind of noise emissions. However, these have the disadvantage that they have to cover a relatively large area and are relatively expensive and space-consuming.
It is therefore an object of the present invention to provide an air filter system in which intake noises are damped within a relatively small space and which can be manufactured at comparatively little expenditures.